An object for recursively pruning empty containers and Nonetypes from containers or sequences.

pruner.py

class Prune:
    'Treat like a function; call Prune.prune on any datatype to prune NoneTypes and empty Tuples/Lists/Dicts.'
    _t = tuple() # Empty tuple, as "(,)" literal doesn't work.
    
    @classmethod
    def prune(self, some_data):
        if isinstance(some_data, (list, tuple)):
            return self.prune_sequence(some_data)
        elif isinstance(some_data, dict):
            return self.prune_tree(some_data)
        else:
            return some_data

    @classmethod
    def prune_tree(self, D):
        'Iterate recursively through dict, building new pruned dict.'
        _D = {}
        for k, v in D.items():
            if v in ({}, [], None, self._t):
                continue
            elif isinstance(v, (dict, tuple, list)):
                _D[k] = self.prune(v)
            else:
                _D[k] = v
        return _D

    @classmethod
    def prune_sequence(self, S):
        'Append pruned sub-units of S to a new sequence of same type.'
        T = type(S)
        _S = []
        for item in S:
            if item in ({}, [], None, self._t):
                continue
            elif isinstance(item, (dict, tuple, list)):
                _S.append(self.prune(item))
            else:
                _S.append(item)            
        return T(_S)